Method of and apparatus for drying- stone or other material



A. W. FRENCH. METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL.

' APPLICATION FILED JUNEZI, 1915: I 1,308,942. 1 Patented .J uly 8, 1919.

5 SHEETS-SHEET I.

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A. W. FRENCH. v

METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL.

APPLICATION FILED JUNE 21. I915.

Patented July 8, 1919.

5 SHEETS-SHEET 2- run COLUMBIA PLANOORAPH-CCL, WASHING'IYJN, 17; C4

A. W. FRENCH.

METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL.

APPLICATION FILED SUNE 21. I915.

5 SHhETSSHE ET 3.

Patented July 8, 1919.

A. W. FRENCH.

METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL. I

APPLICATION FILED JUNE 21. I915- 1,308,942. Patented July 8, 1919.

5 SHEETSSHEET 4- 0 6 n 5 4 I lm g I Q w 3 '02 :0 J. a 3 L q a x A. W. FRENCH.

METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL.

APPLICATION FILED IUNEZI. 1915.

, Patented July 8, 1919.

5 SHEETS-SHEET 5.

unrrnn STATES PATENT OFFICE."

ALFRED W. FRENCH, F PIQUA, OHIO.

METHOD OF AND APPARATUS FOR DRYING STONE OR OTHER MATERIAL.

Specification of Letters Patent.

Patented July 8, 1919.

Application filed June 21, 1915. Serial No. 35,232.

T 0 all whom it may concern:

Be it known that I, ALFRED W. FRENoiI,

V a citizen of the United States, residing at Piqua, in the county of Miami and State of Ohio, have invented a new and useful Irnprovement in Methods of and Apparatus for Drying Stone or other Material, of which the following is a specification. V I

This invention relates to a method of and an apparatus for drying finely divided stone and analogous material, such as limestone in the broken and finely divided condition in which it comes from the quarry, to prepare the same for grinding or other subsequent treatment.

Broken stone consisting of lumps of a size, say from one-half of an inch to two inches, comparatively free from finer stuif can be satisfactorily dried by forcing heated air or other suitable drying medium through the materialin a drying chamber through which the material is caused to pass at a suitably regulated speed. But the stone frequently contains a considerable proportion of fine wet stufi, and it is also desired at times to work up a lot of the finer sand-like material that has been a'cciunulating for a long time and has become soaked with water. It has been found impracticable to dry this fine wet material alone in a drier of the kind mentioned, because the material packs in the drier and is too dense to permit the pro-per passage of air through it, and. when the material consists of mixed broken stone and fine wet stuff, the air will pass through the points of least resistance and will not uniformly dry the material.

The objects of the invention are to devise a method of and an apparatus for efiiciently and economically drying divided material of the nature mentioned, in which the broken stone or coarser material is dried and heated in the drier and mixed with the fine wet material to effect a preliminary drying of the same, the fine stuff, after being dried, being separated from the coarse stone and the latter being again passed through the drier and used over and over again; and

also to improve drying apparatus of this the coarse hot stone.

thereof, on anenlarged scale, showing the drier partly in section.

Fig. 3 is a fragmentary sectional elevation on a still larger scale showing the discharge hopper at the base of the drier.

Fig. 4 is a fragmentary sectional elevation of the apparatus on line 4-4, Fig. 2, on an enlarged scale.

Fig. 5 is a fragmentary sectional elevation thereof online 55, Fig. 4.

Figs. 6 and 7' are diagrammatic views showing alternative forms of the apparatus.

The apparatus and method are intended for use in drying stone of the sort mentioned to prepare the same to be ground or for other treatment, and the material treated in the drying apparatus will be hereinafter referred to as stone but it is not intended thereby to necessarily limit the invention to the drying of such material.

According to this method of drying, the coarse or broken hot stone is mixed with the fine stone to effect the-drying thereof. The

wet stone for the purpose of uniformly dry-' the same. When the fine stone is dried, 1t is separated from the coarse stone, the fine stone being then discharged from the apparatus and the coarse stone returned to the drier. If desired, the mixture of fine and coarse stone can be passed through the drier after'pa rt of the moisture has been removed from the fine Wet stuff by its mixture with By means of this method large quantities of fine stone which have heretofore been considered as waste material, owing to the diffioulties experienced in drying the same, can be made use of.

Briefly stated, the apparatus embodying the invention shown in Figs. 15 c01nprises a drier or drying chamber through which a mixture of fine and coarse material passes, and in which the heating and drying medium is forced through the mass of material to be dried. A hopper is arranged at the bottom of the drier and the material is discharged from this hopper at a properly regulated speed to a screen by which the fine material is separated from the coarse mateoff of the screen is delivered into a receptacle into which the incoming fine wet material is supplied so that the coarse stone imparts its heat to the fine material and effects a preliminary drying thereof. The mixture of fine and coarse material is then carried to the top of the drier by means of a conveyer and passes through the drier for the final drying.

A represents the drier, which may be of any suitable construction adapted to dry the material while passing through the same at a suitably regulated speed. The drier is preferably provided with two upright drying chambers a for the stone separated by an intervening upright passage or chamber a for the air or other drying medium. The drying chambers have opposite walls composed of spaced inclined slats or bafiles a which are staggered so as to cause the stone to be deflected from side to side or agitated in its downward course through the drying chambers. The lower portion of the drier is provided with a jacket or chamber B into which the heated air or other drying medium is admitted and from which it passes through the spaces between the baffles into the lower parts of the drying chambers and through the mass of. stone therein and thence into the central passage a. The drying medium passes upwardly in the air passage and through the mass of stone in the upper parts of the drying chambers and thence to the atmosphere through the open sides of the drier. By means of this construction the fresh incoming drying medium acts on the partly dried stone in the lower part of the drier to complete the drying thereof and then passes through the moist stone in the upper part of the drier, so that an efficient use is made of the heat in the drying medium,

The stone passes from the dryingchambers a a into hoppers O C which discharge the stone into a trough 0 having a discharge opening 0 located intermediate of the ends of the trough. The stone is moved along the trough 0 by suitable means, such as a screw conveyer 0 having right and left handed flights or portions which move the stone from each of the hoppers C to the discharge opening of the trough. The screw conveyer can be driven so as to cause the stone to descend through the drier and be discharged therefrom at the required speed by any suitable means, such as sprocket wheels 0 0 and chain 0 connecting the conveyer to a driving shaft 0.

The stone drops through the discharge opening 0 of the trough a into a casing D having two discharge spouts (Z d controlled by a valve (Z by means of which the stone can be discharged through either of the spouts (Z (Z, depending upon the position of the valve. When the stone passes through the spout d it passes to a screen E, which,

in the construction shown, is an inclined rotary screen having meshes through which the fine material is adapted to pass. The fine material passing through the screen E collects in a hopper F. The'screen E can be driven by any suit-able means, as for instance by bevel gears a connecting the screen shaft 6 to a shaft 6 which is connected to the driving shaft 0 by a sprocket chain 6 and sprocket wheels 6 and 6 Any other suitable means could be employed for screenin the stone after the same passes out of the drier.

The hopper F is provided at its bottom with a trough f in which is a suitable conveyer adapted to move the fine stone lengthwise through the trough to discharge the same from the apparatus. A screw conveyer G is shown for this purpose, which discharges the fine stone into the casing of an elevator H by which it is carried from the apparatus. The screw conveyer G may be driven by any suitable means, such as bevel gears g g connecting the conveyer to a shaft 9 which is connected by a sprocket chain 9 and sprocket wheels 5 g to the shaft 6 which drives the rotary screen The screw conveyers 0 and G are of relatively small diameter so that they are well spaced from the walls of the troughs in which they are located, thereby preventing the material from choking in the troughs and interfering with the operation of the conveyers.

The coarse stone which tails off from the screen E is delivered by an inclined hopper 'or chute I into the casing of an elevator I which carries the stone to the top of the drier and discharges the same into a feed conveyer trough 2' above the drier. A screw conveyer 2" arranged in this trough moves the material lengthwise thereof and drops the same into the drier. Any other means for elevating the stone and feeding the same into the drier may be used.

In order to efliect a preliminary drying of the fine wet material before the same is fed into the drier, a hopper K is provided through which the fine wet material is admitted into the chute I so that it is mixed with the coarse hot stone therein, causing apart of the moisture to be evaporated while the stone is being carried by the elevator I to the top of the drier. This eliminates to a large extent the tendency of the fine stuff to pack or cake in the drier and prevent the free and uniform passage of the drying medium through the material in the drying chambers a (2.

Since the coarse stone is separated from the fine stuff, returned to the drier and used over and over, it gradually accumulates in quantity and when the proportion thereof is too great it becomes necessary to discharge some of the coarse stone.

When it is desired to discharge the coarse stone from the apparatus, the valve d in the casing D is set in the position shown in dotted lines in Fig. 3 to cause the stone to be discharged through the chute cl and thence into a trough or chute Z which connects with the conveyer H, which removes the stone from the apparatus.

Means of any suitable kind may be provided for supplying a heating and drying medium to the drier. The means shown for this purpose comprise a furnace M which has a grate m supporting the fuel and from which heated 'air and products of combustion pass into the chamber or jacket B through a pipe m. Air is blown into the furnace by a suitable blower m having a discharge pipe m adapted to direct air through the chamber over the fire in the furnace, and a branch pipe m controlled by a valve m and conducting air into the furnace below the grate.

In the operation of the apparatus described, the incoming fine wet stuff is introduced into the hopper K and mixes with the coarse hot stone, which has been separated from the fine stuff and is on its return way to the drier, to effect the preliminary drying of the fine stuff. The mixture of coarse and fine stone then passes through the drier and the coarse stone forms suflicient spaces between the particles of the mass to permit the drying medium to flow freely and uniformly through the same.

After passing through the drier the stone is screened and the fine stone discharged from the apparatus While the coarse stone is returned to the drier and used repeatedly.

Figs. 6 and 7 show diagrammatically other arrangements of apparatus whereby fine wet stone may be dried and in which the coarse stone only is passed through the drier and receives suflicient heat to dry the fine stone when mixed with the same. In

' Fig. 6, N represents the drier from which the coarse stone is discharged through a spout 71. into a drying trough n through which the stone is passed by a conveyer in the trough, and partly dried fine stone descends through the passage n and is mixed with the hot coarse stone in passing through the first part of the drying trough n to eifect the final drying thereof. Intermediate of its ends the trough n is provided with a discharge spout n which conducts the material to a screen M. The fine dried stone passes through the screen into a hopper n and is discharged from the apparatus. The coarse stone passes from the screen to an elevator at and is mixed with the incoming fresh wet stone in the hopper n and the mixture then enters the trough n beyond the discharge spout n therein and is carried to the discharge end of the trough n. The material is discharged from the end of the drying trough it into an elevator n and carried by the same to a screen it from which the now partly dried fine stone is discharged into the passage n to be mixed with the hot coarse stone from the drier for its final drying. The coarse stone from the screen a is discharged into a conveyer n which returns it to the drier N.

In the construction shown in .Fig. 7, 0 represents the drier from which the coarse hot stone is discharged by means of-a. spout 0 into a drying trough 0, and fine wet stone is admitted to the trough from a hopper 0 A conveyer in the troughmixes the coarse and fine stone and also passes the same through the trough to a screen 0 The fine stone passing through the screen enters a hopper 0 from which it is discharged from the apparatus. The coarse stone tailing off of the screen is returned to the drier by means of an elevator 0 and a conveyer 0 By means of the several apparatus described, the fine wet stone can be efficiently and economically dried. The agitation of the stone by means of the baflies in the drier and by means of the conveyers, elevators and other parts of the apparatus insures a thorough mixing of the fine and coarse stone and a uniform drying of the fine stone. By causing the stone to be moved continuously through the apparatus, the most efficient use is made of the heat of the drying medium.

I claim as my invention:

1. The herein described method of removing moisture from fine stone consisting in heating a quantity of stone, utilizing the heat of coarse stone for removing moisture from the fine stone by mixing heated coarse stone with moist fine stone, separating the coarse stone from the fine stone, and using the coarse stone repeatedly.

2. The herein described method of drying material, consisting of mixing fine wet material with previously heated coarser material to eifect a thorough mixingof the fine and coarse material, finally drying the fine material, and screening the dried fine material from the coarse material, and again using the coarse material in the drying process.

3. The herein described method of drying material, consisting of mixing fine wet material with previously heated coarser material to effect a preliminary drying of the fine material, passing the mixture of partly dried fine and coarse material through a drier, screening the fine material from the mixture, and again mixing the coarse material with fresh fine material.

4. The herein described method of drying mixed fine and coarse material, consisting in passing the material through a drier and heating the same, then separating the fine material from the coarse material, re-

turning the coarse material toand again passing it through the drier, and feeding fresh material to said heated coarse material While on its return way to the drier.

5. The combination of a drying chamber, means for controlling the movement of ma terial through said chamber, means for heating material in said chamber, means in Which fine material is mixed with heated coarse material, means for separating the fine material from the coarse material, and means for returning the coarse material to said drying chamber.

6. The combination of a drier, means for causing material to move through said drier at a regulated speed, means for heating the material in said drier, means for mixing the wet fine material with heated coarse material to remove moisture from the fine material, and means for discharging the dried fine material from the apparatus.

7. An apparatus for drying material comprising a drying chamber, means for controlling the movement of material through said chamber, means for heating coarse material in said chamber, means in which fine material is mixed with heated coarse material leaving said drying chamber to effect a preliminary drying of the fine material, means for effecting the final drying of the fine material, and means for separating the fine material from the coarse material after such final drying.

8. An apparatus for drying material comprising a drier, means for causing the passage of a mixture of fine and coarse material through said drier, a screen for separating the fine material from the coarse material,

means for discharging the fine material from the apparatus, and means for mixing wet fine material with said coarse material to effect a preliminary drying of the same and returning said mixed material to the drier.

9. An apparatus for drying material comprising an upright drying chamber through which the material is adapted topass by gravity, means for regulating the discharge from said chamber, means for screening the material discharged from the lower end of the drying chamber to separate fine material from the coarse material, means for mixing wet fine material with the separated coarse material, and means for elevating the mixture to the upper end of the drying chamber.

10. An apparatus for drying material, comprising an upright dryin chamber through which the material is adapted to descend, means for regulating the discharge from said chamber, a screen which receives the material from said drying chamber and separates the fine material from the coarse material, a conveyer which receives the coarse material from said screen and returns the same to the drying chamber, and means for supplying fine material to said conveyer ALFRED W. FRENCH.

Witnesses:

R. MIDDY, M. M. WHITLOCK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

